Calibrate 15 inch LVDS

Discussion in 'Android' started by idorel77, Apr 2, 2017.

  1. idorel77

    idorel77 Member

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    Hi ,

    i have udoo quad, last android and udoo LVDS 15 inch with touch.

    How do i calibrate the touch under android? I have to fix about 1 cm to right...

    Thanks.
     
    Last edited by a moderator: Apr 3, 2017
  2. Andrea Rovai

    Andrea Rovai Well-Known Member

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  3. idorel77

    idorel77 Member

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    And how can i calibrate with this file?
     
  4. Andrea Rovai

    Andrea Rovai Well-Known Member

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    I am sorry but I am not able to give you the how-to, I can only point you in the right direction.
     
  5. idorel77

    idorel77 Member

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    helpful like usual ...

    Maybe somebody else can help,
    thanks.
     
  6. Chris_

    Chris_ New Member

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    I had the same problem.
    I solved it like this:

    On the Android 4.4.2 image, you have a TSCalibration-App.
    This apk can be extracted and installed right on the Android 6 image.
    If you do not know how to extract this apk, let me know.

    After you installed the calibration app, you can start it.
    However it will do nothing, because the permission on the file system for the calibration file are incorrect.

    Therefore connect your Udoo via adb and launch the adb shell.
    The calibration file for the touch screen is located in the folder "/sys/module/usbtouchscreen/parameters/" named "calibration".
    Typically this files contains something like this "0,0,0,..."

    Change the permissions of this file such that the previously installed touchscreen calibration app can modify this file.
    This can be done via the command "su -c 'chmod 666 /sys/module/usbtouchscreen/parameters/calibration'

    Note that I had to disable the hardware calibration (file: /sys/module/usbtouchscreen/parameters/hwcalib_xy)
    and disable the swap of xy (file: /sys/module/usbtouchscreen/parameters/swap_xy) for the perfect result of a calibration.
    To disable these you can write a "N" instead of a "Y" in the corresponding files.

    Now the tricky part, as you already modified the calibration by disabling these settings, the touchscreen will not work correctly.
    Therefore use a connected mouse and start the calibration app.
    However, during the calibration in the app itself, you can use the touchscreen.

    After clicking the five targets for the calibration, your touchscreen should be calibrated.
    You can also see this in the file "/sys/module/usbtouchscreen/parameters/calibration" as the numbers are modified.

    Now to the disappointed part of this solution.
    The calibration is resetted every time the device is restarted.
    To avoid this reset, I copied a good calibration file into "/storage/self/primary/calibration" and copy this file (with the additionally disabling of hwcalib_xy and swap_xy) to "/sys/module/usbtouchscreen/parameters/calibration" when the device boots up.

    I do not know, why the application is removed in the Android 6 image as it seems that the app is still necessary.
    Also maybe there is another solution to calibrate the touchscreen persistently, but I did not find it yet. ;)
     
    idorel77 likes this.
  7. idorel77

    idorel77 Member

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    Hi , Thanks a lot Chris i will try .
     

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